Vodafone Ireland say a power outage caused its services to fail earlier.
Phone service and 4G were down across parts of the country. While its broadband service was also affected for some customers.
Problems were reported in Dublin, Cork, Limerick, Galway and other places.
However, the issue was largely resolved as of 3.00pm.
In a statement to Newstalk.com, Vodafone Ireland says:
"As a result of an ESB power outage in Dublin city centre today, a small number of Vodafone customers experienced issues with their fixed services for a short period of time today in certain parts of Dublin, Kildare, Louth, Kerry , Cork and Meath. Mobile services in some parts of the Dublin city centre were also affected for less than half an hour. The fault was identified and full services to customers have been restored. We apologise to our customers for the inconvenience caused."
At its peak, 226 faults were reported - according to irishoutages.com.
Vodafone Ireland says it has over two million customers in Ireland.
Seperatly, users also experienced issues with Outlook and XBox Live services earlier.